Phase shifter, system, chip and radar sensor including plural differential transmission lines that can be adjusted to provide for desired phase shift

The present application is a continuation of PCT Patent Application No. PCT/CN2022/123129, filed Sep. 30, 2022, which is incorporated by reference herein in its entirety.

The disclosure relates to the technical field of radio frequency (RF) phase shifting, and more particularly to a transmission line phase shifter, a system, a chip, and a radar sensor.

In many wireless scenarios, especially in the field of wireless communication and radar sensors, radio frequency (RF) circuits having phase control capabilities can greatly improve information capacity, anti-interference ability, or improve directivity of detection and communication.

Therefore, a phase shifter is introduced in the RF circuit to enable a terminal device to have the phase control capability. Performance of the RF circuit is affected by phase-shifting accuracy, phase-shifting precision, calibration complexity, a calibration duration, and a calibration bandwidth of the phase shifter.

In view of technical deficiencies existed in related technologies, embodiments of the disclosure aim to provide a transmission line phase shifter, a system, a chip, and a radar sensor.

According to a first aspect of the disclosure, a transmission line phase shifter is provided. The transmission line phase shifter includes at least one transmission line phase-shifting unit configured to receive an input radio frequency (RF) signal and to output an output RF signal. A respective transmission line phase-shifting unit of the at least one transmission line phase-shifting unit comprises a first pair of differential transmission lines, a second pair of differential transmission lines, and a phase adjusting circuit. The phase adjusting circuit is configured to receive at least one phase shifting control signal and to adjust electrical parameters of a transmission path according to the at least one phase shifting control signal, so that the output RF signal has a phase shift of a first phase or a second phase relative to the input RF signal, the transmission path including at least one pair of transmission lines of the first pair of differential transmission lines and the second pair of differential transmission lines.

According to a second aspect of the disclosure, a phase shifting system is provided and includes the transmission line phase shifter as described in the first aspect and a phase shifting controller. The transmission line phase shifter includes at least two transmission line phase-shifting units, a second pair of differential transmission lines of each transmission line phase-shifting unit are respectively coupled with a corresponding second pair of differential transmission lines of an adjacent transmission line phase-shifting unit to form a cascaded circuit. The phase shifting controller is coupled to a phase adjusting circuit of each transmission line phase-shifting unit, and is configured to output a plurality of phase shifting control signals to adjust at least one of a capacitance parameter and an inductance parameter of a respective transmission line phase-shifting unit of at least one transmission line phase-shifting unit, for the respective transmission line phase-shifting unit to output a phase-shifted RF signal according to the first phase or the second phase.

According to a third aspect of the disclosure, a RF chip is provided and includes a signal generator, a frequency multiplier, the transmission line phase shifter as described in the first aspect, and a driving amplifier. The signal generator is configured to generate an intermediate frequency signal. The frequency multiplier is coupled with the signal generator and configured to multiply a frequency of the intermediate frequency signal to a frequency of a RF signal. The transmission line phase shifter is coupled with the frequency multiplier and configured to output a phase-shifted RF signal. The driving amplifier is coupled with the transmission line phase shifter and configured to amplify and output the phase-shifted RF signal.

According to a fourth aspect of the disclosure, a radar sensor is provided and includes a transmitting antenna, a receiving antenna, and the RF chip described in the third aspect. The transmitting antenna is configured to radiate an input RF transmitting signal to a free space in a form of a detection signal wave. The receiving antenna is configured to convert an echo signal wave detected into a RF receiving signal, where the echo signal wave is formed by reflection of a detection signal wave by an object. The RF chip is coupled to the transmitting antenna and the receiving antenna, and is configured to output a phase-shifted RF transmitting signal to the transmitting antenna and convert the RF receiving signal into a baseband digital signal to measure the object.

According to a fifth aspect of the disclosure, an apparatus is provided and includes: a radar sensor or a RF chip as described in the foregoing aspects, and an apparatus body, where the radar sensor or the RF chip is arranged on the apparatus body.

Exemplary embodiments may be described more fully with reference to the accompanying drawings. However, the exemplary embodiments can be implemented in a variety of forms and should not be construed as being limited to the embodiments set forth herein. Instead, these embodiments are provided to make the disclosure comprehensive and complete and the idea of the exemplary embodiments will be fully conveyed to those skilled in the art. In the figures, same reference numerals denote same or similar parts throughout the detail description of drawings and thus repetitive descriptions thereof will be omitted.

The described features, structures, or characteristics may be incorporated in one or more embodiments in any suitable manner. In the following illustration, many specific details are provided to give a full understanding of the embodiments of the disclosure. However, those skilled in the art will appreciate that the disclosed technical solutions may be practiced without one or more of these specific details, or implemented with other manners, components, materials, devices, etc.

The flow charts illustrated in the accompanying drawings are merely illustrative and are not necessarily to include all contents and operations/steps nor are they necessarily to be performed in the order described. For example, some operations/steps can also be decomposed, while other operations/steps can be merged or partially merged, so the actual order of execution may change according to the actual situation.

The terms “first”, “second”, etc. in the specification and claims of the disclosure and the above drawings are used to distinguish different objects rather than describe a specific order. Furthermore, the terms “including/comprising” and “having” and any variations thereof are intended to cover non-exclusive inclusion.

Those skilled in the art will appreciate that the accompanying drawings are merely schematic diagrams of the exemplary embodiments and the modules or processes in the drawings are not necessarily necessary for carrying out the disclosure and therefore cannot be used to limit the scope of the disclosure.

The following describes a radar sensor including a phase shifter as an example. According to a working mode configured in the radar sensor, the phase shifter performs a phase shifting operation on a local oscillator signal (also known as a LO signal) and converts the LO signal subjected to the phase shifting into a detection signal wave through a transmitting antenna to be radiated to a free space. When the detection signal wave radiated by the transmitting antenna is reflected by an object to form an echo signal wave, a receiving antenna converts the echo signal wave into a radio frequency (RF) receiving signal. The RF receiving signal is mixed with the LO signal, and then a baseband signal is output. The baseband signal carries phase shifting information provided by the phase shifter, so that a signal processor of the radar sensor can accurately extract a relative physical measurement value of the object from the baseband signal.

In some examples of the radar sensor, the phase shifter is implemented with an in-phase and quadrature (IQ) phase shifter. That is, the phase shifter is configured to convert an input RF signal into an in-phase signal and a quadrature signal, adjust an amplitude of the in-phase signal and an amplitude of the quadrature signal according to a phase shifting control signal, and obtain any phase-shifted RF signal through vector synthesis. However, the IQ phase shifter is an active device, and thus, when pressure voltage temperature (PVT) changes, the IQ phase shifter is hard to be in a stable state. In addition, the IQ phase shifter has obvious nonlinear characteristics, and thus there is a need to adopt single-point calibration. For example, preset phase shifting points need to be calibrated one by one. It can be understood that complexity of the calibration and a time length for the calibration may limit working efficiency of the radar sensor.

Embodiments of the disclosure provide a transmission line phase shifter. The transmission line phase shifter includes at least one transmission line phase-shifting unit. Each transmission line phase-shifting unit includes a plurality of groups of transmission lines (with or without ground wires) and a plurality of phase adjusting circuits. Different groups of transmission lines have different closed path lengths for RF currents, and correspondingly equivalent inductances are different. Some phase adjusting circuits of the phase adjusting circuits are connected between the plurality of groups of transmission lines or between a respective transmission line and a corresponding ground wire for switching signals to be transmitted on different transmission lines or different ground wires, so as to adjust an equivalent inductance L corresponding to transmission lines. Therefore, the same phase adjusting circuits are referred to as an inductance adjusting circuit. In the remaining phase adjusting circuits of the phase adjusting circuits, at least one switched capacitor is connected between different transmission lines or between a respective transmission line and a corresponding ground wire, so as to adjust an equivalent capacitance C corresponding to the transmission lines, so the remaining phase adjusting circuits are referred to as a capacitance adjusting circuit. Since an insertion phase φ of the transmission line phase-shifting unit has a corresponding relationship φ=ω(VLC) with the equivalent inductance L and the equivalent capacitance C, an insertion phase φ of the transmission line phase-shifting unit can be adjusted through the plurality of phase adjusting circuits (i.e., the inductance adjusting circuit and the capacitance adjusting circuit), such that phase shifting can be realized. The insertion phase generally refers to a phase shift between an input signal and a corresponding output signal.

By controlling a state of a corresponding phase adjusting circuit, the transmission line phase-shifting unit can be configured to have at least two states, for example, a first phase state (also called a reference state) and a second phase state (also called a phase shifting state). An equivalent inductance and an equivalent capacitance of the transmission line phase-shifting unit in the first phase state are respectively denoted as Land C, and an equivalent inductance and an equivalent capacitance of the transmission line phase-shifting unit in the second phase state are respectively denoted as Land Crespectively. An insertion phase of the transmission line phase-shifting unit in the first phase state is denoted as (1 and an insertion phase of the transmission line phase-shifting unit in the second phase state is denoted as φ. A difference between the insertion phase of the transmission line phase-shifting unit in the first phase state (reference state) and the insertion phase of the transmission line phase-shifting unit in the second phase state (phase shifting state) is called a phase shifting amount, which is denoted as Δφ. Therefore,Δφ=φ−φ=ω(√{square root over ()})−ω(√{square root over ()}).In other embodiments, the transmission line phase-shifting unit can also be configured to have three or more states. As can be seen, the phase adjusting circuit can adjust electrical parameters of a transmission path where a corresponding group of transmission lines of the plurality of groups of transmission lines is located according to at least one phase shifting control signal received, so that a RF signal output from the transmission line phase-shifting unit has a phase shift of at least a first phase (first phase shift) or a second phase (second phase shift) relative to an input RF signal of the transmission line phase-shifting unit.

In terms of basic structure types of transmission lines, the transmission line phase-shifting unit generally includes a single-ended transmission line phase-shifting unit and a differential transmission line phase-shifting unit.

As an example, a transmission line phase-shifting unit constituted by single-ended transmission lines includes a single-ended signal line, a first pair of ground wires, and a second pair of ground wires. As illustrated in, a single-ended signal line Sand a first pair of ground wires (G-, G-) constitute a first group of transmission lines, and the single-ended signal line Sand a second pair of ground wires (G-, G-) constitute a second group of transmission lines. Different equivalent inductances are realized by using a difference between a spacing dbetween one ground wire of the first pair of ground wires and the signal line as well as a spacing dbetween one ground wire of the second pair of ground wires and the signal line. Different equivalent capacitances are realized by using switched capacitors between the signal line and a corresponding ground wire. The switched capacitors and a circuit for switching different ground wires are all included in a phase adjusting circuit.

As another example, a transmission line phase-shifting unit constituted by differential transmission lines includes a first pair of differential transmission lines, a second pair of differential transmission lines, and a ground wire, where the ground wire is optional. As shown in, signal lines Sig_P and Sig_N constitute a first group of transmission lines, and signal lines Sig_P and Sig_N constitute a second group of transmission lines The signal lines Sig_P and Sig_N and the signal lines Sig_P and Sig_N are all differential transmission lines. Different equivalent inductances are realized by using a difference between a spacing between the first group of differential transmission lines PN and a spacing between the second group of differential transmission lines PN. Different equivalent capacitances are realized by using switched capacitors between differential transmission lines. The switched capacitors and a circuit for switching different differential transmission lines are all included in a phase adjusting circuit.

In order to enable the transmission line phase-shifting unit have stable electrical characteristics and good differential symmetry (the latter is merely for the differential transmission line phase-shifting unit), the transmission line phase-shifting unit is generally symmetric in structure, where an axis of symmetry (also known as a symmetry axis) is a center line of the transmission line phase-shifting unit and is parallel to a direction of signal transmission, such as a virtual axis line (a dash-dotted line) inor. The virtual axis line is used for indicating that the transmission lines are symmetrical and is not a physical transmission line. The physical transmission line may overlap or partially overlap with the virtual axis line For example, as shown in, the signal line Sin the single-ended transmission line phase-shifting unit is overlapped with the virtual axis line. The ground wire G-and the ground wire G-in the first pair of ground wires have an equal first spacing dwith respect to the signal line S. The ground wire G-and the ground wire G-in the second pair of ground wires have an equal second spacing dwith respect to the signal line S. For another example, the physical transmission line may be not overlapped with the virtual axis line. As shown in, the signal line Sig_P and the signal line Sig_N in the first pair of differential transmission lines in the differential transmission line phase-shifting unit have an equal first spacing dwith respect to the virtual axis line (a dash-dotted in the figure) The signal line Sig_P and the signal line Sig_N in the second pair of differential transmission lines have an equal second spacing dwith respect to the virtual axis line.

It is to be noted that physical variables such as the phase shifting amount, and the spacing, etc. involved in the disclosure are to be understood as physical variables falling within an engineering error range.

show layout of the single-ended transmission line phase-shifting unit and the differential transmission line phase-shifting unit, where all the groups of transmission lines in the transmission line phase-shifting unit are located on a same metal layer. In other examples, all the groups of transmission lines are located on different metal layers, or even on stacked metal layers. In addition, in the example ofandB, a spacing between a group of transmission lines corresponding to a smaller insertion phase is less than a spacing between another group of transmission lines corresponding to a larger insertion phase. In other examples, the spacing between any two of different groups of transmission lines may also be the same/similar, and different groups of transmission lines correspond to different transmission line lengths, to enable an equivalent inductance L/equivalent capacitance C corresponding to each group of transmission lines to meet a desired adjustment range. Therefore, a desired phase shifting amount Δφ is achieved, and impedance matching may be maintained during phase shifting.

The phase adjusting circuit is a circuit designed according to the above principle for outputting at least one phase shifting control signal. The phase shifting control signal is provided according to the number of controlled devices and controlled electrical parameters in the phase adjusting circuit. In some examples, one phase shifting control signal is used for controlling the controlled devices according to adjustable electrical parameters, such as a voltage, a current, and a duty cycle of the phase-shifting control signal. For example, a voltage of one channel of phase shifting control signal can be used for adjusting an on/off state of a switch tube. For another example, a voltage (or current) of another channel of phase shifting control signal can enable the switch tube to provide different impedance in a linear region range. Alternatively, a voltage (or current) of yet another channel of phase shifting control signal can enable the switch tube to be in a cut-off region or saturation region. Alternatively, a duty cycle of yet another channel of phase shifting control signal can adjust a charging/discharging time length of a capacitor, to further adapt to a corresponding phase state switching due to a change of capacitance of the capacitor. In other examples, multi-channel of phase shifting control signals constitute a coded signal to control a controlled array to adjust a capacitance parameter and/or inductance parameter of the whole circuit. For example, the multi-channel of phase shifting control signals can adjust the number of on/off switches in the controlled switch array to adjust the corresponding capacitance parameters and/or inductance parameters.

Therefore, the phase adjusting circuit in the transmission line phase-shifting unit may include switch tubes for switching different groups of transmission lines, or switch tubes for causing different groups of transmission lines to transmit RF signals of different flow amounts, etc. Correspondingly, a switch tube manufactured by a semiconductor process can be switched in a saturation region or a cut-off region according to a phase shifting control signal. A resistance value of another switch tube manufactured by the semiconductor process can be adjusted in a linear region between the saturation region and the cut-off region by adjusting the phase shifting control signal, so that different groups of transmission lines transmit shunted RF signals. The phase adjusting circuit may further include capacitors and resistors to adapt to the capacitance and/or resistance values in the equivalent circuit required for the corresponding phase state, i.e., to change the capacitance parameters and/or inductance parameters of the transmission line phase-shifting unit. In this way, it is possible to achieve phase shifting of the RF signal, and further realize impedance matching between the transmission line phase-shifting unit and an external circuit. The external circuit is, for example, a driving amplifier circuit in a RF chip, or other circuits for receiving a RF signal subjected to phase shifting, etc.

According to the above formula of the phase shifting amount, the phase adjusting circuit can independently adjust the equivalent inductance or the equivalent capacitance in the transmission line phase-shifting unit. In order to keep the transmission lines to be in a matching state before and after phase shifting, characteristic impedance Zc of the transmission lines before and after phase shifting is required to remain unchanged. According to a formula

a ratio of the equivalent inductance L to the equivalent capacitance (should be kept unchanged before and after the phase shifting. Therefore, it is necessary to adjust the equivalent inductance and the equivalent capacitance. For the RF circuit, when some electronic devices (such as different groups of transmission lines and switch tubes) are adjusted, capacitance parameters and inductance parameters may be changed at the same time. The types of different controlled circuits in the phase adjusting circuit described in the disclosure should be distinguished and understood from the perspective of mainly adjusting the capacitance parameters or inductance parameters of the whole transmission line phase-shifting unit.

The phase adjusting circuits include the inductance adjusting circuit. The inductance adjusting circuit is configured to adjust inductance parameters (e.g., inductances or resistance values) of the transmission line phase-shifting unit under the control of the phase shifting control signal, so that the transmission line phase-shifting unit performs a phase shifting operation according to the first phase or the second phase.

In some examples, group-based selection of different groups of transmission lines is performed by using controlled devices such as switch tubes and adjustable resistors, or switch tubes and adjustable inductors, so that the transmission line phase-shifting unit achieves state switching in the first phase or the second phase.

As shown in, the following describes a single-ended transmission line phase-shifting unit as an example of the transmission line phase-shifting unit. In some examples, the inductance adjusting circuit is a circuit used for performing switching between a first pair of ground wires or a second pair of ground wires. For example, the inductance adjusting circuit includes a first switch tube connected between the ground wire G-in the first pair of ground wires and the ground wire G-in the second pair of ground wires, and a second switch tube connected between the ground wire G-in the first pair of ground wires and the ground wire G-in the second pair of ground wires. When the transmission line phase-shifting unit is configured in the first phase state, the first switch tube and the second switch tube are switched on, so that the phase shifting operation is performed through the single-ended signal line Sand the first pair of ground wires (G-, G-). When the transmission line phase-shifting unit is configured in the second phase state, the first switch tube and the second switch tube are turned off, so that the phase shifting operation is performed through the single-ended signal line Sand the second pair of ground wires (G-, G-).

In other examples, the inductance adjusting circuit is a circuit for adjusting flow amounts of RF signals in the first pair of ground wires and the second pair of ground wires. For example, the inductance adjusting circuit includes a third switch tube (e.g., a metal oxide semiconductor tube) connected between the ground wire G-in the first pair of ground wires and the ground wire G-in the second pair of ground wires, and a fourth switch tube (e.g., a metal oxide semiconductor tube) connected between the ground wire G-in the first pair of ground wires and the ground wire G-in the second pair of ground wires. When the phase shifting operation is performed on input RF signals according to the first phase, the third switch tube and the fourth switch tube are operated in the saturation region or the linear region, such that a flow amount of RF signals flowing through a transmission path in which the single-ended signal line Sand the first pair of ground wires (G-, G-) are located is greater than a flow amount of RF signals flowing through a transmission path in which the single-ended signal line Sand the second pair of ground wires (G-, G-) are located. When the phase shifting operation is performed on the input RF signals according to the second phase, the third switch tube and the fourth switch tube are operated in the cut-off region or the linear region, such that the flow amount of the RF signals flowing through the transmission path where the single-ended signal line Sand the second pair of ground wires (G-, G-) are located is greater than the flow amount of the RF signals flowing through the transmission path where the single-ended signal line Sand the first pair of ground wires (G-, G-) are located.

The following describes a differential transmission line phase-shifting unit as an example of the transmission line phase-shifting unit. An inductance adjusting circuit in the differential transmission line phase-shifting unit includes a switch tube, where the switch tube is used for selecting different groups of transmission lines. For example, as shown in, the inductance adjusting circuit includes at least two switch tubes (sw_sig, sw_sig). One switch tube sw_sigis connected between the signal line Sig_P in the second pair of differential transmission lines and the signal line Sig_P in the first pair of differential transmission lines. The other switch tube sw_sigis connected between the signal line Sig_N in the second pair of differential transmission lines and the signal line Sig_N in the first pair of differential transmission lines. The signal line Sig_P and the signal line Sig_P are both used for transmitting a same RF P signal in a group of differential RF signals, and the signal line Sig_N and the signal line Sig_N are both used for transmitting a same RF N signal in the group of differential RF signals.

When the phase shifting operation is performed on the input RF signals according to the second phase, the switch tube sw_sigand the switch tube sw_sigare turned off, so that the RF signals are transmitted via the second pair of differential transmission lines Sig_P and Sig_N. When the phase shifting operation is performed on the input RF signals according to the first phase, the switch tube sw_sigand the switch tube sw_sigare turned on, so that the RF signals are transmitted via the first pair of differential transmission lines Sig_P and Sig_N.

The phase adjusting circuit further includes a capacitance adjusting circuit. The capacitance adjusting circuit is configured to adjust capacitance parameters of the transmission line phase-shifting unit under the control of at least one input phase shifting control signal so that the transmission line phase-shifting unit selects to perform a phase shifting operation according to the first phase or the second phase. The capacitance adjusting circuit is a controlled circuit that provides an adjustable capacitance, and can be adjusted according to capacitance required by the transmission line phase-shifting unit in a state of the first phase or the second phase (i.e., the first phase state or the second phase state).

The capacitance adjusting circuit provides adjustment based on a variable capacitance circuit. The capacitance adjusting circuit includes, for example, at least one of following controlled circuits: a switched capacitor array, and a variable capacitance circuit including at least one varactor diode. The switched capacitor array includes a plurality of groups of series circuits, each group of series circuits including a switch tube and a capacitor. Each switch tube is selectively turned on or off according to a corresponding input phase shifting control signal. In the variable capacitance circuit including the at least one varactor diode, a capacitance value of each varactor diode is adjusted according to the phase shifting control signal inputted.

In the above variable capacitance circuit, a switched capacitor providing a fixed capacitance value can be included to provide a basic capacitance value for the capacitance adjusting circuit, and other variable capacitance circuits are used for adjusting a total capacitance value based on the basic capacitance value. In the variable capacitance circuit of the above fixed and/or variable capacitance, a switch tube can be optionally included, and the switch tube can be used as an adjustment mechanism according to an input control signal. By adjusting a conduction state of the switch tube, it is possible to enable the switch tube not only to work in the off state and the on state, but also work in a plurality of semi-conduction states between the off state and the on state, which is equivalent to controlling the capacitance value.

The capacitance adjusting circuit can be coupled between a respective transmission line for transmitting RF signals and a corresponding reference ground. As an example, the capacitance adjusting circuit in the single-ended transmission line phase-shifting unit is coupled between the signal line and any ground wire. As another example, as shown in, the differential transmission line phase-shifting unit further includes a ground wire Gnd_P and a ground wire Gnd_N. A metal is connected between the ground wire Gnd_P and the ground wire Gnd_N to form an equipotential circuit. Each transmission line in a same group of transmission lines is coupled with the ground wire Gnd_P or the ground wire Gnd_N via a corresponding capacitance adjusting circuit. For example, as shown in, the capacitance adjusting circuit includes two groups of series-connected capacitors cap and switch tubes sw_cap, where each capacitor cap and a corresponding switch tube sw_cap in a same group are connected in series. One group of series-connected capacitor cap and switch tube sw_cap is connected between the ground wire Gnd_P and the signal line Sig_P, and another group of series-connected capacitor cap and switch tube sw_cap is connected between the ground wire Gnd_N and the signal line Sig_N. In order to make the differential transmission line phase-shifting unit have a symmetrical arrangement to maintain symmetry of differential RF signals, the capacitance adjusting circuit is symmetrically arranged in an integrated circuit.

In order to simplify circuit complexity of the differential transmission line phase-shifting unit and maintain the signal symmetry of the differential signal, so as to facilitate phase shifting and signal transmission by utilizing anti-interference property of the RF signal, the spacing (as shown in, double d(2×d)) between the first pair of differential transmission lines and a length of each transmission line in the first pair of differential transmission lines are configured according to the inductance parameter and the capacitance parameter that correspond to the first phase.

The following describes the differential transmission line phase-shifting unit as an example. As shown inand, the capacitance adjusting circuit is connected between the second pair of differential transmission lines (Sig_P, Sig_N). The capacitance adjusting circuit includes capacitors capand capas shown inthat are arranged symmetrically with respect to the virtual axis line and a switch tube sw_cap. One end of the capacitor capis connected to the signal line Sig_P of the second pair of differential transmission lines and the other end of the capacitor capis connected to the switch tube sw_cap. One end of the capacitor capis connected to the signal line Sig_N of the second pair of differential transmission lines and the other end of the capacitor capis connected to the switch tube sw_cap. The operating process of the capacitance adjusting circuit is illustrated as follows. For example, under the control of the phase shifting control signal, when the switch tube sw_cap is turned on, the transmission line phase-shifting unit performs a phase shifting operation on the input RF signals according to the second phase. When the switch tube sw_cap is turned off, the transmission line phase-shifting unit performs a phase shifting operation on the input RF signals according to the first phase. For another example, under the control of the phase shifting control signal, when the switch tube sw_cap provides a large resistance value by using semiconductor characteristics, it is equivalent to adjusting flow amount configuration of the RF signals in the two pairs of differential transmission lines, so that a current quantity of the RF signals transmitted through the second pair of differential transmission lines (Sig_P, Sig_N) is larger than a current quantity of the RF signals transmitted through the first pair of differential transmission lines (Sig_P, Sig_N). Therefore, the transmission line phase-shifting unit performs the phase shifting operation on the input RF signals according to the second phase. When the switch tube sw_cap provides a small resistance value by using the semiconductor characteristics, it is equivalent to adjusting flow amount configuration of the RF signals in the two pairs of differential transmission lines, so that the current quantity of the RF signals transmitted through the second pair of differential transmission lines (Sig_P, Sig_N) is smaller than the current component of the RF signals transmitted through the first pair of differential transmission lines (Sig_P, Sig_N). Therefore, the transmission line phase-shifting unit performs the phase shifting operation on the input RF signals according to the first phase.

Each controlled circuit described above may be connected to a corresponding transmission line according to a position relationship between the transmission lines and a position where each circuit device is disposed. For example, in a stacked semiconductor structure, the phase adjusting circuit may be connected to the corresponding transmission line through a metal via hole and/or a conductor such as a microstrip line. In order to systematically suppress jitter, phase-shifting drift, common mode in differential signals, and other aspects of the transmission line phase-shifting unit generated when the transmission line phase-shifting unit performs the phase shifting, the transmission line phase-shifting unit further includes multiple bridges. Each bridge may include a microstrip line, or a microstrip line and a metal via hole. All the bridges are symmetrically arranged to symmetrically couple other electrical devices in the phase adjusting circuit to corresponding transmission lines. In this way, the whole symmetric circuit structure of the transmission line phase-shifting unit is realized. For example, as shown in, bridges Brg_, Brg_, and Brg_are coupled between the signal line Sig_N and the signal line Sig_N, and bridges Brg_, Brg_, and Brg_are coupled between the signal line Sig_P and signal line Sig_P. Bridges Brg_and Brg_are symmetrically arranged with respect to the direction of the signal transmission. Bridges Brg_and Brg_are symmetrically arranged with respect to the direction of the signal transmission. Bridges Brg_and Brg_are symmetrically arranged with respect to the direction of the signal transmission. In addition, the bridges Brg_and Brg_are symmetrically arranged with respect to the bridge Brg_, and the bridges Brg_and Brg_are symmetrically arranged with respect to the bridge Brg_. The capacitance adjusting circuit and the inductance adjusting circuit each are symmetrically connected to the bridges, to realize the whole axisymmetric circuit structure of the transmission line phase-shifting unit.

In some examples not shown, some electrical devices in the capacitance adjusting circuit and the inductance adjusting circuit can be coupled to different connection points of a same bridge to reduce the number of bridges, thereby simplifying the circuit structure and improving the overall circuit stability of the transmission line phase-shifting unit.

In some embodiments, in order to reduce interference of the electromagnetic radiation of the differential transmission line phase-shifting unit on signals of other circuits in the integrated circuit, for example, to reduce the interference of the electromagnetic radiation on a signal of a low frequency circuit, the transmission line phase-shifting unit further includes a grounding conductor disposed around the first pair of differential transmission lines and the second pair of differential transmission lines. The grounding conductor is configured to provide electromagnetic shielding of the differential transmission line phase-shifting unit. The grounding conductor can be omitted or retained.

In some examples, the grounding conductor is located at least on a metal layer between the transmission line phase-shifting unit and other circuits according to a position relationship between the transmission line phase-shifting unit and the other circuits. For example, a grounding conductor in a shape of a grounding metal strip is formed on the metal layer. There are a plurality of grounding metal strips, which are arranged as a grounding conductor including grid-shaped strips arranged at intervals. For example, the grounding conductor is formed on the metal layer between the differential transmission line phase-shifting unit and the other circuits, and the grounding conductor is also symmetrical in structure to effectively shield electromagnetic radiation. As shown inor, the grounding conductor includes the ground wires Gnd_P and Gnd_N and the metal wire connected between the ground wires. As shown in, an envelope size of the grounding conductor i.e., the ground wires GND_P and GND_N in the figure is larger than an envelope size of the transmission line phase-shifting unit, e.g., each of the ground wires Gnd_P and Gnd_N in the grounding conductor is disposed on a corresponding signal line of the second pair of transmission lines (Sig_P and Sig_N) away from a respective signal line of the first pair of transmission lines (Sig_P and Sig_N). Alternatively, as shown in, the envelope size of the grounding conductor i.e., the ground wires GND_P and GND_N in the figure is smaller than the envelope size of the transmission line phase-shifting unit, e.g., the grounding conductor is disposed between the second pair of transmission lines (Sig_P and Sig_N).

In other examples, the grounding conductor is formed by using a metal layer between the transmission line phase-shifting unit and a package structure of the integrated circuit.

In still other examples, a three-dimensional grounding conductor is formed using a metal layer around each of the transmission line phase-shifting units and a grounding via hole between corresponding metal layers for accommodating a transmission line phase shifter.

The transmission line phase shifter includes a plurality of transmission line phase-shifting units. At least one group of transmission lines of the plurality of transmission line phase-shifting units are coupled with each other to form a cascaded circuit. The cascaded transmission line phase-shifting units can provide a same phase shifting amount or different phase shifting amounts. A state in which each of all the transmission line phase-shifting units in the transmission line phase shifter is in a respective first phase sate is called as a reference state of the transmission line phase shifter, and a state in which each of all the transmission line phase-shifting units is in a respective second phase state is called as a phase shifting state of the transmission line phase shifter. For example, a first phase and a second phase of each of the cascaded transmission line phase-shifting units are respectively identical with a first phase and a second phase of any other transmission line phase-shifting unit according to a predetermined phase shifting step of the radar sensor. In addition, each of the transmission line phase-shifting units can be individually controlled by a corresponding phase shifting control signal so that the transmission line phase shifter can provide a phase shifting operation of an integral multiple of the phase shifting step. The phase shifting step is a phase shifting amountof a single transmission line phase-shifting unit in the transmission line phase shifter.

The transmission line phase-shifting units are electrically coupled with each other through at least one group of transmission lines in each transmission line phase-shifting unit to form a cascaded circuit. For example, as shown in, in the radar sensor, a single-ended signal line S, a first pair of ground wires (G-and G-), and a second pair of ground wires (G-and G-) in each of a plurality of single-ended transmission line phase-shifting units are metal wires that are integrally manufactured. Each transmission line phase-shifting unit utilizes a corresponding phase adjusting circuit to provide a phase shifting operation. As another example, in the radar sensor, the single-ended signal line Sand the second pair of ground wires (G-and G-) in each of the plurality of single-ended transmission line phase-shifting units are metal wires that are integrally manufactured. Each transmission line phase-shifting unit utilizes a corresponding phase adjusting circuit to enable RF signals to be transmitted along different groups of transmission lines, so as to provide a phase shifting operation.

For the RF signal, due to the electromagnetic characteristics of the RF signal and a relatively long total length of each transmission line in the transmission line phase shifter, a total phase shifting amount and a phase shifting deviation of the transmission line phase shifter are restricted by each other. When the number of transmission line phase-shifting units in the transmission line phase shifter is relatively large, the total phase shifting amount of the whole transmission line phase shifter is relatively large. However, in this case, since the transmission line has a relatively long length, the electromagnetic radiation generated by the long transmission line when transmitting the RF signal easily causes nonlinear phase shifting deviation of the whole transmission line phase shifter.